A general gas turbine is provided with a compressor which produces compressed air, a combustor which produces combustion gas by using the compressed air produced in the compressor, and a turbine which is rotationally driven by the combustion gas produced in the combustor.
The combustor of the gas turbine mixes the compressed air compressed in the compressor with fuel and burns the mixture. However, at this time, there is a case where large combustion oscillation occurs. One of the causes of the combustion oscillation is that pressure fluctuation in a combustion chamber causes variation in a fuel flow rate in a main nozzle which injects fuel. If the fuel flow rate in the main nozzle varies, heat generation fluctuation when burning the fuel occurs according to the flow rate fluctuation. The heat generation fluctuation further causes pressure fluctuation in the combustor.
Japanese Unexamined Patent Application, First Publication No. 2011-137629 discloses a technique in which in order to realize an acoustic characteristic in which it is hard for a fuel flow rate in a main nozzle to respond to pressure fluctuation in a combustion chamber, an orifice for reducing a flow path cross-sectional area is provided in a fuel pipe on the upstream side of a manifold from which a main nozzle branches and is connected thereto.